1. Field of the Invention
The present invention relates to a copier, facsimile apparatus, printer or similar image forming apparatus and more particularly to an image forming apparatus using a process cartridge, which includes a developing device including a toner storing section, and a toner cartridge storing fresh toner for replenishment.
2. Description of the Background Art
It is a common practice with an image forming apparatus to use an image carrier, charger, a developing device and cleaning device implemented as replaceable expendables. For example, the developing device, storing toner therein, is removably mounted to the body of an image forming apparatus and replaced when it runs out of toner. Although this scheme reduces the size of a replaceable unit, it makes not only a mechanism but also work for replacement itself sophisticated.
In light of the above, the image carrier, charger and other expendables and the developing device, storing toner therein, may be constructed into a single process cartridge, in which case the process cartridge will be bodily replaced when the developing device runs out of toner. With the process cartridge, it is possible to effect toner replenishment and the replacement of expendables at the same time for thereby simplifying maintenance. However, when the process cartridge is operated in a condition that consumes much toner, it must be wastefully replaced despite that the number of prints output is small and therefore the expendables are still usable.
Japanese Patent Laid-Open Publication No. 10-239974, for example, discloses a process cartridge configured to replenish toner from a toner bottle, which is removably disposed in the cartridge, to a developing device, thereby obviating the wasteful replacement of the expendables mentioned above. However, the process cartridge taught in the above document has a problem that the toner bottle cannot be replaced unless the entire process cartridge is removed from the body of an image forming apparatus, resulting in troublesome replacement.
To solve the above problem, Japanese Patent Laid-Open Publication No. 11-231631, for example, teaches an image forming apparatus with a process cartridge and a toner bottle removable independently of each other. The toner bottle and process cartridge adjoin each other and are removable from the body of the apparatus independently of each other. However, when the toner bottle and process cartridge are positioned close to each other, the apparatus becomes bulky because optimum design for reducing the size of the apparatus is not attainable. This is particularly true with a color image forming apparatus including four or more toner bottles and four or more process cartridges.
Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 9-160364, 2001-27839, 2002-6601, 2002-244359 and 2002-268357.